Correlation and Variation in the Toad 579 



be measured the following day. In no case was any measurement 

 taken from an individual which had been more than twenty-seven 

 hours in captivity. 



Fig. I Ventral view of female toad in position for measurement. One-half natural size of toad 

 weighing 41.0 grams. 



The characters measured and methods of measurement are 

 briefly as follows: (Compare with Fig. i.) 



1 Total weight. The toad was brushed rlean and weighed alive. 'There was a gradual loss in 

 weight during captivity chiefly due to defecation and evaporation of water. The rate per cent at which 

 this loss occurred was determined in four series of different sized toads and the proper correction made 

 for each individual according to hours elapsed from time of collection. Usually upon opening the abdom- 

 inal cavity the bladder and alimentary canal were found empty; in the few individuals where this was 

 not the case, proper correction was again made. The toad was then pithed (brain and cord) a broad 

 incision being made to permit free loss of blood. While taking the succeeding measurements the toad 

 was placed on its back and the blood drained off completely. For the next measurements the legs were 

 placed in the position shown in Fig. i. 



2 Length of body. From tip of nose to end of body between thighs. This of course includes 

 the head. 



3 Length of thigh. One-half the distance between the middles of the knee-joints when in the 

 position shown in the figure. 



4 Length of shank. Distance from middle of knee-joint to middle of ankle-joint. 



5 Length of foot. Distance from middle of ankle-joint to tip of longest (second) toe when fully 

 extended. 



6 Length of leg. Sum of thigh, shank and foot. 



7 Total length. Sum of body and leg. 



8 Width of mouth. Transverse extent between angles of mouth when closed. 



9 Length of head. Distance from tip of nose to postero-dorsal margin of cranium exposed by 

 pithing incision. 



